This description relates to a distributed database system.
A database is a structured set of persistent data that can be managed and queried using a software program. A transactional database management system is a relational database system that operates on (e.g., stores and manipulates) data in a database using database “transactions.” In general, a database transaction symbolizes a single unit of work (including one or more operations) performed by the database management system on the database. To ensure that database transactions are processed reliably, database transactions must be atomic (i.e., a transaction, including all of its one or more operations, must either complete in its entirety or have no effect whatsoever), consistent (i.e., a transaction must move the database from one valid state to another valid state), isolated (i.e., concurrently executing transactions result in the same state in the database as would result if the transactions were executed serially), and durable (i.e., a committed transaction will remain committed regardless of system crashes, errors, and other issues). This set of properties of a database transaction is sometimes referred to as “ACID.”